It is first obtained on the first level: Dark Secret. It's in Kessler's house, on a table with a Thompson and binoculars. It can also be found on the Forest Compound level. Later in the game, it can be obtained from killed enemies or found in secret areas.

This gun uses 7.92mm ammunition and has a 10-round magazine with a maximum reserve supply of 200 rounds.

The Mauser rifle is the same weapon but without a scope. It is technically a separate weapon which shares the same ammo. However, the Sniper Scope replaces the Mauser Rifle in your inventory. You cannot use the Mauser once you have picked up a Sniper Scope.

For some reason, simply looking through the scope increases damage almost three times (55 hit points vs 20).

It doesn't have visible crosshairs when not zoomed in.

The scope has a bar on the right that changes from red to green and gets smaller when you hold still. That bar indicated to the player how much accuracy they had.

When looking through the scope, there is a vertical bar on the left side of the screen which gets smaller and changes from red to green if you hold still or move very slowly. The smaller the bar is, the greater your accuracy. When you first look through the scope, the bar is completely filled, making this weapon a poor choice for rapid aiming and firing.

Even though it is not specified in-game, it is reasonable to assume that this is a Gewehr 98 due to the rear sight being a quadrant sight, and it lacking the front sight hood of the later Kar98ks. The Gewehr98 was replaced by the kar98k in 1935 and manufactured by Mauser, and that was the primary German service rifle until the end of World War II in 1945. It would be more likely that they would have used the Kar98k or Gewehr 43.

Both the Gewehr 98's and Kar98k's real-life capacity is 5 rounds. In reality the German rifle with a 10 round capacity, the Gewehr 43, was semi automatic.